In order to shape cardboard and other such materials use is made of rotating tools, for example, rotating knives, rotating compressors, driving cutting wheels, stencillers and segmented knives, which are mounted on rotating shafts. These different tools are attached to annular cutter blocks which are composed of two substantially symmetrical, semi-circular elements assembled on the drive shaft.
Having regard to the dimensions of the cuts which are to be made and to the processes which are to be carried out in the shaping of the cardboard, the cutter blocks have to be able to be positioned on the drive shafts in a precise and continuous way. Different processes for attaching cutter blocks on to shafts are known. Firstly, there are purely mechanical processes, such as clamping the shaft between the two symmetrical elements of the cutter block by means of a screw, or supporting a screw on a pin while the two symmetrical elements of the cutter block are put into place by means of a screw, but are not locked in relation to the shaft.
Secondly, there are processes involving distortion by the action of pressure, for example, distortion of the shaft by subjecting it to an internal hydraulic pressure, thereby to apply the shaft to a cutter block which is already in place but is not locked, or the distortion of a toric inflatable bag positioned between the shaft and the elements of the cutter block resting on the pins for example.
These various processes of attachment require more or less delicate adjustments in order to ensure correct positioning of the cutter blocks and effective locking of the cutter blocks with respect to the drive shaft. In effect it is necessary to provide for the displacement of the cutter blocks at each change in production, and this makes it essential to be able to make the necessary adjustments quickly. With the systems of clamping use a pin or an inflatable bag positional adjustments cannot be quickly carried out. The system using distortion of the shaft improves the adjustment time and functions well, but is very onerous.